Casual dress codes have become standard in many workplaces, especially in young startups. It's increasingly acceptable in many offices to find employees wearing T-shirts, shorts, sandals, or with visible tattoos and piercings.

But relaxed or vague company dress codes can lead to misunderstanding and even lawsuits. For example, a former U.S. Marine recently filed suit against Union Pacific Railroad after he was fired for his military-related upper-arm tattoo that was termed obscene and threatening. The veteran is currently seeking lost wages and punitive damages for discrimination, retaliation and wrongful firing in federal court.

So how do employers tread the thin line between fostering a relaxed and creative work environment while making sure that employees' tattoos or clothing isn't offensive to others in the office?

Tamara Devitt, managing partner at labor law firm Fisher & Phillips in Los Angeles, recommends that employers with relaxed dress code standards take measures to ensure that an employee’s ink, piercing or clothing is not offensive to someone else in the office. Here’s her list of recommended do's and don’ts:

1. Do have (or update) your appearance and dress code policy. Employers must have published rules in place. Your policy should clearly explain the image the company presents to its customers or clients and that all employees are expected to comply with the policy.

2. Don't assume "one size fits all." When crafting a policy, take into consideration your company's culture. Some employers might seek to prohibit any visible tattoos or body piercings, even if it makes it harder to recruit potential talent, while in other industries such forms of "self-expression" might be the norm.

3. Do consider a multi-tiered approach. Some employers permit tattoos or piercings for those not working with customers. But if an employer allows visible tattoos or piercings, it should make a provision prohibiting tattoos that could be considered harassing or discriminatory of others in the workplace.

4. Don't forget about workplace anti-discrimination laws. While it’s generally permissible for an employer to prohibit visible body art and/or piercings as part of facially neutral policies, they may run afoul of anti-discrimination laws. Specifically, most employers are required to accommodate religious beliefs. An employer may be required to accommodate a tattoo, piercing or other (such as head coverings) if it relates to an employee's religion.

As with any employment decision, one of the keys to avoiding liability for discrimination and related employment claims is consistent enforcement of workplace policies. If you have any doubts about your company’s appearance and dress code policy, seek the advice of legal counsel.